The present invention relates to a process-gas supply apparatus for supplying a process gas into a process chamber arranged in a process apparatus such as a semiconductor manufacturing apparatus and having a object to be processed set therein.
Generally, in a manufacturing process of a semiconductor integrated circuit, a film formation process, pattern etching, and the like, are repeatedly applied onto a semiconductor wafer or a glass substrate, thereby obtaining a desired device. Recently, line width and gate width have become narrow associated with a tendency toward miniaturization and high integration of the semiconductor integrated circuit. Also, the film thickness tends to be reduced since the semiconductor integrated circuit is increasingly desired to have a multilevel interconnection structure.
As mentioned above, when the thickness of the formed film is reduced as a result of the high integration and the multi-layer tendency of the integrated circuit, it becomes critical to control a flow amount of a process gas accurately for forming a film. To control the flow amount accurately, a flow-amount controller such as a mass-flow controller is generally used in the semiconductor manufacturing apparatus. However, the mass-controller is not suitable for controlling a small amount of a gas flow for the reason of its structural characteristics. In fact, it is difficult to accurately form a gate electrode and wiring of several hundreds of angstroms in thickness under the control by the mass-flow controller.